A116947 Numbers k such that 4*k^6 + 1 is prime.
1, 2, 3, 5, 7, 17, 20, 22, 28, 30, 40, 45, 67, 68, 70, 75, 82, 85, 87, 88, 95, 108, 123, 125, 140, 150, 153, 163, 172, 190, 197, 200, 210, 217, 220, 223, 232, 237, 248, 268, 270, 282, 283, 287, 303, 310, 320, 333, 340, 358, 367, 403, 405, 407, 423, 438, 445, 447
Offset: 1
Examples
If k=197 then (4*k^6 + 1) is a prime with 15 digits.
Programs
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Mathematica
Select[Range[500], PrimeQ[(4*#^6 + 1)] &] (* Stefan Steinerberger, Apr 06 2006 *)
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PARI
is(n)=isprime(4*n^6+1) \\ Charles R Greathouse IV, Jun 13 2017
Extensions
More terms from Stefan Steinerberger, Apr 06 2006